A device limit is the maximum number of computers, phones, or tablets that a security subscription will cover under one plan. It is a licensing rule, not a security feature, but it strongly affects how much protection a product can actually provide in a home or small business.
This matters because attackers often exploit the weakest, least protected device in a network. If a plan only covers some endpoints, the remaining devices may be left exposed to phishing, malware, or ransomware. In real use, device limits shape how defenders deploy antivirus, web protection, or scam detection across a family or team. Buyers should check whether the limit is per account, per user, or per device, and whether reinstalling or replacing hardware counts against the allowance.